I saw what great thinkers could do once they cut loose from the religious jargon of mental fog bank religion holds forth as knowledge. If this were compressed into a single person it would be Carl Sagan. The grace of proper perspective can't be faked. Religious people keep appearing to me as full blown dumb asses who evade causality. The software upgrade bombed. Luddites seeking more luddites bore me.

This is a late response but I'd have to say F, B ( though it was multiple books), G , and O. Since for most people ( in my observable experience) come to the realization that they are atheist after long dragged out periods of time it is difficult to pin it on one event.

As for O, things I saw and read on the Internet. The Atheist Experience and info on the Council of Nicea to name two off hand.

Mostly F)... I was more interested in facts of science and mathematics as a child, and matters of the divine seemed useless to me.

I would say, though, that much of my later exposure to expressions of religion (particularly after I entered the U.S.), and many of the typical atheist literature did inspire me to be more vocal in my disapproval.

An addendum. I'm wondering if others had found the change, or part of it, traumatic.

Getting down from the agnostic fence required only an easy jump. Climbing onto the fence fifty years earlier, after twelve years in Catholic schools (for which I do not thank my dad) required me to make a lot of new brain connections. When my mom told me I was going to college because I was too lazy to find and keep a job, she broke the connections that 12 years of Catholic dogma had made.

It hurt, and knowing she wouldn't have said that unless my dad had agreed, I threw them out of my life. After three years I made an uneasy truce. One day, her manner very different, she told me a woman she had met in PTA had congratulated her on my graduation. My dad's offer to loan me money for a year of graduate school surprised me; it may have been his way of making amends.

Telling myself that parents have to earn honor was a part of my breaking with Catholicism.